As the use of touch screens, such as for public information kiosks, portable devices, and gaming applications and the like, increases, so does the need for more durable touch screen designs. Use of lamination configurations is a known technique to enhance durability of and add features (such as conductive, anti-glare, and anti-reflective coatings) to the touch screens. For example, using a transparent, conductively coated flexible plastic material, such as transparent conductively coated PET laminated to ultrathin glass (having a glass thickness preferably less than about 0.3 mm in thickness, more preferably less than about 0.2 mm in thickness, most preferably less than about 0.1 mm thickness) as the top sheet in a conventional resistive touch screen design (as shown in FIG. 1) is known in the art of touch screen manufacturing. The coating of flexible PET with a transparent conductive coating, such as by a web coating process, is also common process knowledge.
A conventional resistive touch screen device is shown in FIG. 1. In this device, a resistive touch screen 60 uses a transparent rigid substrate 10, which can be glass or plastic. A transparent conductive thin film 20 (such as indium tin oxide in the sheet resistance range of about 150 to about 900 ohms per square, sometimes in the range of about 400 to about 600 ohms per square with a physical thickness of about 500 angstroms or less) may be deposited onto a surface 24 of substrate 10. Insulating spacer dots 30 (as known in the interactive information display art), may be arranged on surface 22 of transparent conductive film 20, in order to provide separation between surface 22 and a second transparent conductive film 51 (that is deposited on a flexible substrate 50) so as to avoid false-touch sensing of the touch screen. The transparent conductive film 51 is typically indium tin oxide, and may be deposited using a conventional coating deposition technique know as physical vapor deposition (preferably by web coating) on flexible transparent substrate 50, typically PET. This flexible transparent substrate may be laminated or attached using conventional adhesive materials to the ultrathin glass substrate 40.
Although the above configuration can work well in certain circumstances, steps involved in laminating the PET substrate to the ultrathin glass substrate can be challenging and costly. Thus, there is a need for a more economical way of furnishing a transparent conductive coated, ultrathin glass top sheet for a display device, in particular, a resistive touch device.